The present invention relates to silyl (meth)acrylate copolymers, processes for preparing the same, antifouling paint compositions containing the silyl (meth)acrylate copolymers, antifouling coating films formed from the antifouling paint compositions, antifouling methods using the antifouling paint compositions, and hulls or underwater structures coated with the coating films.
More particularly, the invention relates to silyl (meth)acrylate copolymers which can produce antifouling paints capable of forming antifouling coating films which hardly suffer from occurrence of cracks, have excellent adhesive strength and thereby hardly suffer from peeling, can be favorably controlled in the hydrolysis rate, and are excellent in antifouling performance (antifouling activities), antifouling properties, particularly antifouling properties in a highly fouling environment, and long-term antifouling properties. The invention also relates to processes for preparing such copolymers, antifouling paint compositions capable of forming antifouling coating films having the above properties, antifouling coating films formed from the antifouling paint compositions, antifouling methods using the antifouling paint compositions, and hulls or underwater structures coated with the coating films.
Ships"" bottoms, underwater structures, fishing nets, etc. sometimes have bad appearances and lose their functions, when they are exposed to water for a long time and various aquatic organisms, for example, animals such as oysters, hard-shell mussels and barnacles, plants such as laver, and aquatic bacteria adhere and propagate thereon.
Especially when such aquatic organisms adhere and propagate on a ship""s bottom, the surface roughness of the whole ship may be increased to induce decrease of velocity of the ship or increase of fuel consumption. Further, removal of such aquatic organisms from the ship""s bottom needs much labor and a long period of working time. In addition, if bacteria adhere and propagate on an underwater structure and slime (sludge-like substance) further adheres thereto to bring about decomposition of the bacteria, or if large-sized organisms adhere and propagate on an underwater structure such as a steel structure to damage anticorrosive coating films of the underwater structure, the strength or the function of the underwater structure may be lowered to thereby extremely shorten the lifetime of the underwater structure.
In order to prevent such problems, ships"" bottoms have been hitherto coated with antifouling paints of excellent antifouling properties, for example, a paint containing a copolymer of tributyltin methacrylate and methyl methacrylate or the like and cuprous oxide (Cu2O). The copolymer contained in this antifouling paint is hydrolyzed in seawater to release an organotin compound such as bistributyltin oxide (tributyltin ether, Bu3Snxe2x80x94Oxe2x80x94SnBu3 (Bu: butyl group)) or tributyltin halide (BU3SnX (X: halogen atom)) and exerts an antifouling effect, and besides the hydrolyzed copolymer itself becomes water-soluble and is dissolved in seawater. That is, this antifouling paint is a xe2x80x9chydrolyzable self-polishing paintxe2x80x9d, so that no resin residue remains on the coated surface of the ship""s bottom, and the surface can be always kept active.
Such organotin compounds, however, are strongly toxic, and there are fears of marine pollution, occurrence of malformed fish or malformed shellfish and evil influences on the biosystem due to the food chain. For this reason, development of tin-free antifouling paints substitutable for the conventional paints has been desired.
The tin-free antifouling paints are, for example, silyl ester antifouling paints described in (1) Japanese Japanese Patent Laid-Open Publication No. 264169/1992 and (3) Japanese Patent Laid-Open Publication No. 264168/1992. These antifouling paints, however, have problems of poor antifouling properties and occurrence of cracking or peeling, as taught by (4) Japanese Patent Laid-Open Publication No. 157941/1994 and (5) Japanese Patent Laid-Open Publication No. 157940/1994.
In (6) Japanese Patent Laid-Open Publication No. 196869/1990, an antifouling paint containing a chemically modified acid functional copolymer (A), which is obtained by copolymerizing trimethylsilyl methacrylate, ethyl methacrylate and methoxyethyl acrylate in the presence of an azo polymerization initiator and contains a carboxylic acid group blocked by a trimethylsilyl group, and a compound (B) of a polyvalent cation is taught. This antifouling paint, however, has a problem that a coating film obtained from the antifouling paint is not satisfactory in the crack resistance.
In (7) National Publication No. 500452/1985 of International Patent Application and Japanese Patent Laid-Open Publication No. 215780/1988, a resin for an antifouling paint, which is obtained by copolymerizing a vinyl monomer having an organosilyl group such as a trialkylsilyl ester of (meth)acrylic acid with another vinyl monomer and has a number-average molecular weight of 3,000 to 40,000, is described. It is also described that an organic water binder such as trimethyl orthoformate, an antifouling agent such as cuprous oxide and a pigment such as red iron oxide can be further added. This resin for an antifouling paint, however, has problems that the resin is liable to be gelatinized when stored and a coating film formed from the antifouling paint has poor crack resistance and peel resistance, as described in (5) Japanese Patent Laid-Open Publication No. 157940/1994.
In Japanese Patent Publication No. 32433/1993 corresponding to the above-mentioned publication (7) (National Publication No. 500452/1985 of International Patent Application), an antifouling paint comprising (a) a toxic substance and (b) a polymer binder which has a recurring unit represented by the formula (xe2x80x94CH2xe2x80x94CXCOOR)xe2x80x94(B)xe2x80x94 (X is H or CH3, R is SiRxe2x80x23 or Si(ORxe2x80x2)3, Rxe2x80x2 is an alkyl group or the like, and B is a residual group of an ethylenically unsaturated monomer) and has a specific hydrolysis rate is disclosed. It is also described that a solvent, a water-sensitive pigment component, an inert pigment, a filler and a retarder can be further introduced. The coating film obtained from the antifouling paint described in this publication, however, has a problem of poor crack resistance.
In (8) Japanese Patent Laid-Open Publication No. 18216/1995, there is disclosed a paint composition which contains, as its major components, (A) a polymer of an organosilicon-containing monomer A having an organosilicon triester group represented by the formula (I) xe2x80x94COOxe2x80x94SiR1R2R3 (R1 to R3 are each an alkyl group of 1 to 18 carbon atoms or the like) in a molecule and (B) copper or a copper compound and further contains, as an essential component other than the components (A) and (B), an alkoxy group-containing silicon compound represented by the following formula (C): 
wherein R4 to R6 are each a hydrogen atom, an alkoxy group of 1 to 18 carbon atoms, a cycloalkoxy group or the like, R7 is an alkyl group of 1 to 18 carbon atoms or the like, and n is an integer of 1 to 3.
In the above publication, it is also described that a copolymer AB of the monomer A having a group represented by the formula (I) and a vinyl monomer B copolymerizable with the monomer A may be contained. Further, (meth)acrylic esters such as methyl (meth)acrylate, ethyl (meth)acrylate and dimethylaminoethyl (meth)acrylate are given as examples of the monomer B.
The coating film obtained from the paint composition described in the above publication, however, has a problem that a coating film obtained from the paint composition is poor in the crack resistance and the antifouling properties, particularly antifouling properties in a highly fouling environment. The term xe2x80x9chighly fouling environmentxe2x80x9d indicates, for example, a sea area rich in nutritive such as inland sea or a state where a ship or structure is allowed to stand in such a sea area or a ship frequently repeats running and stopping or runs at a low rate, e.g., about 10 knots or lower.
In (9) Japanese Patent Laid-Open Publication No. 102193/1995, there is disclosed a paint composition containing, as its essential components, a copolymer of a monomer mixture consisting of a monomer A represented by the formula Xxe2x80x94SiR1R2R3 (R1 to R3 are each a group selected from an alkyl group and an aryl group and may be the same or different, and X is an acryloyloxy group, a methacryloyloxy group, a malenoyloxy group or a fumaroyloxy group) and a monomer B represented by the formula Yxe2x80x94(CH2CH2O)nxe2x80x94R4 (R4 is an alkyl group or an aryl group, Y is an acryloyloxy group or a methacryloyloxy group, and n is an integer of 1 to 25), and an antifouling agent. Further, inorganic compounds such as copper compounds (specifically, cuprous oxide and copper powder), zinc sulfate and zinc oxide, and metal-containing organic compounds such as organocopper compounds (specifically, oxine copper), organonickel compounds and organozinc compounds (specifically, zinc pyrithione) are given as examples of the antifouling agents. In this publication, however, neither an organosilyl ester group-containing polymer using 2-hydroxyethyl acrylate or the like nor an organosilyl ester group-containing polymer having both of a straight-chain alkyl group-containing silyl (meth)acrylate constituent unit and a branched alkyl group-containing silyl (meth)acrylate constituent unit is mentioned. In addition, the paint described in this publication is poor in the antifouling properties or the antifouling properties in a highly fouling environment.
In (10) Japanese Patent Laid-Open Publication No. 199095/1996, there is disclosed a paint composition containing, as its essential components, a copolymer of a monomer mixture consisting of the same monomer A represented by the formula (1) Xxe2x80x94SiR1R2R3 as described in the above publication No. 102193/1995, a monomer B represented by the formula (2) Yxe2x80x94(CH(R4))xe2x80x94(OR5) (R4 is an alkyl group, R5 is an alkyl group or a cycloalkyl group, and Y is an acryloyloxy group, a methacryloyloxy group, a maleinoyloxy group or a fumaroyloxy group), and if necessary, a vinyl monomer C copolymerizable with the monomers A and B, and an antifouling agent. Further, acrylic esters, methacrylic esters, styrene and vinyl acetate are described as examples of the vinyl monomers C; and inorganic compounds such as copper compounds (specifically, cuprous oxide and copper powder), zinc sulfate and zinc oxide, and metal-containing organic compounds such as organocopper compounds (specifically, oxine copper), organonickel compounds and organozinc compounds (specifically, zinc pyrithione) are given as examples of the antifouling agents.
In (11) Japanese Patent Laid-Open Publication No. 269388/1996, there is disclosed a paint composition containing, as its essential components, a copolymer of a monomer mixture consisting of a monomer A represented by the formula (1) Xxe2x80x94SiR1R2R3 (R1 to R3 are each a hydrocarbon group of 1 to 20 carbon atoms and may be the same or different, and X is an acryloyloxy group, a methacryloyloxy group, a malenoyloxy group, a fumaroyloxy group or an itaconoyloxy group) and a monomer B represented by the formula (2) Yxe2x80x94(CH2CH2O)nxe2x80x94R4 (R4 is an alkyl group or an aryl group, Y is an acryloyloxy group, a methacryloyloxy group, a maleinoyloxy group, a fumaroyloxy group or an itaconoyloxy group, and n is an integer of 1 to 25), and a copper salt of bis(2-pyridinethiol-1-oxide) (copper pyrithione). Further, dimethyl-t-butylsilyl acrylate is given as an example of the monomer A; and inorganic compounds such as copper compounds (specifically, cuprous oxide and copper powder), zinc sulfate and zinc oxide, and metal-containing organic compounds such as organocopper compounds (specifically, oxine copper), organonickel compounds and organozinc compounds (specifically, zinc pyrithione) are given as examples of the antifouling agents. Furthermore, rosin and rosin derivatives are cited as dissolution rate adjusting agents which can be added to the paint composition.
In (12) Japanese Patent Laid-Open Publication No. 269389/1996, a paint composition comprising a copolymer of a monomer mixture consisting of an unsaturated monomer A having a triorganosilyl group and a monomer B represented by any one of the following formulas (2) to (9), and an antifouling agent is disclosed.
The monomers B are as follows:
a tertiary amino group-containing monomer represented by the formula (2) CH2xe2x95x90CR4COOR5xe2x80x94NR6R7 (R4 is H or CH3, R5 is an alkylene group, and R6 and R7 are each an alkyl group and may be the same or different),
a quaternary ammonium salt-containing monomer represented by the formula (3) CH2∇CR8COOR9xe2x80x94NR10R11R12(Y) (R8 is H or CH3, R9 is an alkylene group, R10 to R12 are each an alkyl group and may be the same or different, and Y is a halogen atom),
a monomer represented by the formula (4) CH2xe2x95x90CHxe2x80x94Z (Z is a group comprising a N-containing heterocyclic ring) and containing a nitrogen-containing heterocyclic ring,
a monomer represented by the formula (5) CH2xe2x95x90CR13COO(R14O)m(R15O)n(R16O)oxe2x80x94R17 (R13 is H or CH3, R14 is an ethylene group, R15 is an alkylene group of 3 carbon atoms, R16 is an alkylene group of 4 carbon atoms, R17 is an alkyl group or an aryl group, m, n and o are each an integer of 0 or greater, and n and o are not 0 at the same time) and having an alkoxy group or an aryloxyalkylene glycol group in a molecule,
a (meth)acrylamide represented by the formula (6) CH2xe2x95x90CR18CONR19R20 (R18 is H or CH3, and R19 and R20 are each an alkyl group and may be the same or different),
a (meth)acrylamide represented by the formula (7) CH2xe2x95x90CR21CON()Q (R21 is H or CH3, N()Q is a N-containing group, and Q may contain O, N, S or the like) and containing a nitrogen-containing cyclic hydrocarbon group,
a furan ring-containing (meth)acrylic ester represented by the formula (8) CH2xe2x95x90CR23COOCH2xe2x80x94T (R23 is H or CH3, and T is a furan ring or a tetrahydrofuran ring), and
a monomer represented by the formula (9) CH2xe2x95x90CHxe2x80x94CN.
Further, various copolymerizable monomers such as acrylic acid, ethyl acrylate, 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (methacrylate are given as examples of the optional components copolymerizable with the monomers A and B.
Although a copolymer comprising tri-n-butylsilyl acrylate (TBSA), diethylaminoethyl methacrylate (DEAEMA) and methyl methacrylate (MMA) and a copolymer comprising tri-n-butylsilyl acrylate (TBSA), N,N-dimethyl acrylamide (DMAA) and methyl methacrylate (MMA) are shown in the examples, neither a copolymer using 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate or the like nor a copolymer using at least straight-chain group-containing silyl (meth)acrylate and branched alkyl group-containing silyl (meth)acrylate is mentioned.
In addition, the same antifouling agents as described in the aforesaid Japanese Patent Laid-Open Publication No. 269388/1996 are given as components which can be added to the paint composition.
In (13) Japanese Patent Laid-Open Publication No. 269390/1996, there is disclosed a paint composition comprising a polymer using a monomer A represented by the formula (1) Xxe2x80x94SiR1R2R3 (R1 to R3 are each a group selected from an alkyl group and an aryl group and may be the same or different, and X is an acryloyloxy group, a methacryloyloxy group, a malenoyloxy group, a fumaroyloxy group or an itaconoyloxy group), a polymer using a monomer B represented by the formula (2) Yxe2x80x94(CH2CH2O)nxe2x80x94R4 (R4 is an alkyl group or an aryl group, Y is an acryloyloxy group, a methacryloyloxy group, a maleinoyloxy group, a fumaroyloxy group or an itaconoyloxy group, and n is an integer of 1 to 25), and an antifouling agent. In this publication, the same antifouling agents as described in the aforesaid Japanese Patent Laid-Open Publication No. 269388/1996 are mentioned. Further, a resin (e.g., rosin) and an anti-settling agent are mentioned as components which can be added to the paint composition.
In (14) Japanese Patent Laid-Open Publication No. 277372/1996, there is disclosed a paint composition which contains a copolymer of a monomer mixture consisting of the same monomer A represented by the formula (1) Xxe2x80x94SiR1R2R3 as described in the aforesaid publication (11) (Japanese Patent Laid-Open Publication No. 269388/1996) and the same monomer B represented by the formula (2) Yxe2x80x94(CH2CH2O)nxe2x80x94R4 as described in the aforesaid publication (11) and a triphenylboron pyridine complex and in which the resin component is composed of only a polymer containing no metal and the aquatic organism adhesion inhibitor is composed of only an organic inhibitor containing no metal. Further, rosin and rosin derivatives are cited as dissolution rate adjusting agents which can be added to the paint composition.
In (15) Japanese Patent Laid-Open Publication No. 30071/1998, there is disclosed a paint composition comprising (A) at least one of rosin and a rosin compound comprising a rosin derivative or a rosin metallic salt, (B) a polymer of at least one monomer M represented by the formula (1) Xxe2x80x94SiR1R2R3 (R1 to R3 are each a group selected from an alkyl group and an aryl group and may be the same or different, and X is an acryloyloxy group, a methacryloyloxy group, a malenoyloxy group, a fumaroyloxy group, an itaconoyloxy group or a citraconoyloxy group) and/or an organosilyl ester group-containing polymer comprising a polymer of at least one monomer M and at least one polymerizable monomer other than the monomer M, and (C) an antifouling agent. In this publication, acrylic acid, methyl acrylate, 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate are given as other monomers (optional components) copolymerizable with the monomer M, but any organosilyl ester group-containing polymer using 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate or the like is not mentioned at all.
In the above publication, the same antifouling agents as described in the aforesaid Japanese Patent Laid-Open Publication No. 269388/1996 are mentioned. Further, a pigment, chlorinated paraffin, an anti-settling agent, etc. are described as components which can be added to the paint composition.
In the publications (9) to (15), however, neither an organosilyl ester group-containing polymer using 2-hydroxyethyl acrylate or the like nor a copolymer using at least straight-chain alkyl group-containing silyl (meth)acrylate and branched alkyl group-containing silyl (meth)acrylate in combination is mentioned. In addition, the paint compositions described in these publications have a problem that the resulting coating films have poor crack resistance or the resulting coating films are insufficient in the balance of various properties such as crack resistance, peel resistance (adhesive strength), antifouling performance, antifouling properties, particularly antifouling properties in a highly fouling environment, long-term antifouling properties and self-polishing properties.
In (16) Japanese Patent Publication No. 82865/1993, 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate are described as copolymerizable components optionally used. In (17) Japanese Patent Laid-Open Publication No. 48947/1997, (18) Japanese Patent Laid-Open Publication No. 48948/1997, (19) Japanese Patent Laid-Open Publication No. 48949/1997, (20) Japanese Patent Laid-Open Publication No. 48950/1997, (21) Japanese Patent Laid-Open Publication No. 48951/1997, (22) Japanese Patent Publication No. 32433/1993, (23) U.S. Pat. No. 4,593,055, (24) Japanese Patent Laid-Open Publication No. 1968669/1990 and (25) WO 91/14743, silyl (meth)acrylate copolymers are described. In the publications (16) to (25), however, neither a copolymer using a hydroxy-containing monomer nor a copolymer using at least straight-chain alkyl group-containing silyl (meth)acrylate and branched alkyl group-containing silyl (meth)acrylate in combination is mentioned. In addition, the antifouling paint using the copolymers described in the publications (16) to (25) have room to be improved in the crack resistance of the resulting coating films and the balance of various properties such as crack resistance, peel resistance (adhesive strength), antifouling performance, antifouling properties, particularly antifouling properties in a highly fouling environment, long-term antifouling properties and self-polishing properties.
In (26) Japanese Patent Laid-Open Publication No. 215780/1988, a copolymer using methyl methacrylate, n-butyl methacrylate, acrylamide or the like is described, and an antifouling paint comprising this copolymer and cuprous oxide is described, but the antifouling paint has the same problems as those of the antifouling paints described in the above publications.
The present invention is intended to solve such problems associated with the prior art as mentioned above, and it is an object of the invention to provide a silyl (meth)acrylate copolymer which can produce an antifouling paint capable of forming an antifouling coating film which hardly suffers from occurrence of cracks, has excellent adhesive strength and thereby hardly suffers from peeling, can be favorably controlled in the hydrolysis rate, and is excellent in antifouling performance (antifouling activities), antifouling properties, particularly antifouling properties in a highly fouling environment, and long-term antifouling properties.
It is another object of the invention to provide a process for preparing the silyl (meth)acrylate copolymer.
It is a further object of the invention to provide an antifouling paint composition capable of forming such an antifouling coating film as mentioned above.
It is a still further object of the invention to provide an antifouling coating film formed from the antifouling paint composition, an antifouling method using the antifouling paint composition and a hull or an underwater structure coated with the coating film.
In the present invention, a first silyl (meth)acrylate copolymer (A-1) or a second silyl (meth)acrylate copolymer (A-2) is used as a copolymer.
The first silyl (meth)acrylate copolymer (A-1) according to the invention comprises:
(a) silyl (meth)acrylate constituent units represented by the following formula (I) in amounts of 20 to 80% by weight: 
wherein R1 is a hydrogen atom or a methyl group, and R2, R3 and R4 may be the same or different and are each an alkyl group, a cycloalkyl group or a phenyl group which may have a substituent group,
(b) acrylic unsaturated monomer constituent units represented by the following formula (II) in amounts of 0.01 to 40% by weight: 
wherein R5 is a hydrogen atom or a methyl group, Z is an oxygen atom or xe2x80x94NR7, when Z is an oxygen atom, R6 is a hydroxyalkyl or hydroxycycloalkyl group which may have a substituent group or a polyalkylene glycol group represented by the formula xe2x80x94(R8O)nH (wherein R8 is an alkylene group and n is an integer of 2 to 50), and when Z is xe2x80x94NR7, R7 is an alkyl group which may be substituted with any of a halogen, a hydroxyl group, an amino group, a substituted amino group, an acyl group and an alkoxy group, and R6 is a hydrogen atom, and
(c) unsaturated monomer constituent units other than the constituent units (a) and (b) in amounts of 5 to 79.99% by weight,
with the proviso that the total amount of the constituent units (a), (b) and (c) is 100% by weight,
said silyl (meth)acrylate copolymer (A-1) having a weight-average molecular weight, as measured by gel permeation chromatography (GPC), of not more than 200,000.
In a preferred embodiment of the silyl (meth)acrylate copolymer (A-1) of the invention, the unsaturated monomer constituent units (c) are those derived from at least one compound selected from (meth)acrylic esters, styrene and vinyl esters.
The process for preparing a silyl meth(acrylate) copolymer (A-1) according to the invention comprises polymerizing:
(a-1) silyl (meth)acrylate represented by the following formula (I-a) in an amount of 20 to 80% by weight: 
wherein R1 is a hydrogen atom or a methyl group, and R2, R3 and R4 may be the same or different and are each an alkyl group, a cycloalkyl group or a phenyl group which may have a substituent group,
(b1) an acrylic unsaturated monomer represented by the following formula (II-a) in an amount of 0.01 to 40% by weight: 
wherein R5 is a hydrogen atom or a methyl group, Z is an oxygen atom or xe2x80x94NR7, when Z is an oxygen atom, R6 is a hydroxyalkyl or hydroxycycloalkyl group which may have a substituent group or a polyalkylene glycol group represented by the formula xe2x80x94(R8O)nH (wherein R8 is an alkylene group and n is an integer of 2 to 50), and when Z is xe2x80x94NR7, R7 is an alkyl group which may be substituted with any of a halogen, a hydroxyl group, an amino group, a substituted amino group, an acyl group and an alkoxy group, and R6 is a hydrogen atom, and
(c1) an unsaturated monomer other than the monomers (a1) and (b1), which is copolymerizable with the monomers (a1) and (b1), in an amount of 5 to 79.99% by weight,
with the proviso that the total amount of said monomers (a1), (b1) and (c1) is 100% by weight,
in the presence of a radical polymerization initiator to obtain the above-mentioned silyl (meth)acrylate copolymer (A-1).
In a preferred embodiment of the process for preparing a silyl (meth)acrylate copolymer (A-1) according to the invention, the unsaturated monomer (c1) is at least one compound selected from (meth)acrylic esters, styrene and vinyl esters.
The silyl (meth)acrylate copolymer (A-2) according to the invention comprises:
(d) silyl (meth)acrylate constituent units represented by the following formula (III):
xe2x80x94CH2xe2x80x94CR(COOSiR11R12R13)xe2x80x83xe2x80x83(III)
wherein R is a hydrogen atom or a methyl group, R11 and R12 are each independently a straight-chain alkyl group of 1 to 10 carbon atoms, a phenyl group which may have a substituent group or a trimethylsilyloxy group, and R13 is an alkyl group of 1 to 18 carbon atoms which may have a cyclic structure or a branch, a phenyl group of 6 to 10 carbon atoms which may have a substituent group or a trimethylsilyloxy group,
(e) silyl (meth)acrylate constituent units represented by the following formula (IV):
xe2x80x94CH2xe2x80x94CR(COOSiR14R15R16)xe2x80x83xe2x80x83(IV)
wherein R is a hydrogen atom or a methyl group, R14 and R15 are each independently a branched alkyl or cycloalkyl group of 3 to 10 carbon atoms, and R16 is a straight-chain alkyl group of 1 to 10 carbon atoms, a branched alkyl or cycloalkyl group of 3 to 10 carbon atoms, a phenyl group of 6 to 10 carbon atoms which may have a substituent group or a trimethylsilyloxy group, and
(f) unsaturated monomer constituent units other than the constituent units (d) and (e),
said silyl (meth)acrylate copolymer (A-2) having a weight-average molecular weight (Mw), as measured by gel permeation chromatography (GPC), of not more than 200,000.
In the second silyl (meth)acrylate copolymer (A-2) of the invention, it is preferable that R11, R12 and R13 are each independently methyl, ethyl, n-propyl, n-butyl, n-hexyl or trimethylsilyloxy.
In the second silyl (meth)acrylate copolymer (A-2) of the invention, it is preferable that R14, R15 and R16 are each independently isopropyl, sec-butyl, tert-butyl or isobutyl.
In the present invention, the unsaturated monomer constituent units (f) are preferably those derived from at least one compound selected from (meth)acrylic esters, styrene and vinyl esters of organic carboxylic acids.
In the present invention, the silyl (meth)acrylate constituent units (d), the silyl (meth)acrylate constituent units (e) and the unsaturated monomer constituent units (f) are preferably present in amounts of 0.5 to 50% by weight, 10 to 70% by weight, and 20 to 70% by weight, respectively, with the proviso that the total amount of the constituent units (d), (e) and (f) is 100% by weight.
The silyl (meth)acrylate copolymer (A-2) of the invention preferably has a weight-average molecular weight (Mw) of 3,000 to 100,000.
The process for preparing a silyl meth(acrylate) copolymer (A-2) according to the invention comprises polymerizing:
(d1) silyl (meth)acrylate represented by the following formula (III-d):
CH2xe2x95x90CR(COOSiR11R12R13)xe2x80x83xe2x80x83(III-d)
wherein R is a hydrogen atom or a methyl group, R11 and R12 are each independently a straight-chain alkyl group of 1 to 10 carbon atoms, a phenyl group which may have a substituent group or a trimethylsilyloxy group, and R13 is an alkyl group of 1 to 18 carbon atoms which may have a cyclic structure or a branch, a phenyl group of 6 to 10 carbon atoms which may have a substituent group or a trimethylsilyloxy group,
(e1) silyl (meth)acrylate represented by the following formula (IV-d):
CH2xe2x95x90CR(COOSiR14R15R16)xe2x80x83xe2x80x83(IV-d)
wherein R is a hydrogen atom or a methyl group, R14 and R15 are each independently a branched alkyl or cycloalkyl group of 3 to 10 carbon atoms, and R16 is a straight-chain alkyl group of 1 to 10 carbon atoms, a branched alkyl or cycloalkyl group of 3 to 10 carbon atoms, a phenyl group of 6 to 10 carbon atoms which may have a substituent group or a trimethylsilyloxy group, and
(f1) an unsaturated monomer other than the monomers (d1) and (e1), which is copolymerizable with the monomers (d1) and (e1),
in the presence of a radical polymerization initiator to obtain the above-mentioned silyl (meth)acrylate copolymer (A-2).
In the process for preparing a silyl (meth)acrylate copolymer (A-2) according to the invention, it is preferable that R11, R12 and R13 are each independently methyl, ethyl, n-propyl, n-butyl, n-hexyl or trimethylsilyloxy.
In the process for preparing a silyl (meth)acrylate copolymer (A-2) according to the invention, it is preferable that R14, R15 and R16 are each independently isopropyl, sec-butyl, tert-butyl or isobutyl.
In the present invention, the unsaturated monomer (f1) is preferably at least one compound selected from (meth)acrylic esters, styrene and vinyl esters of organic carboxylic acids.
In the present invention, the silyl (meth)acrylate (d1), the silyl (meth)acrylate (e1) and the unsaturated monomer (f1) are preferably used in amounts of 0.5 to 50% by weight, 10 to 70% by weight, and 20 to 70% by weight, respectively, with the proviso that the total amount of the components (d1), (e1) and (f1) is 100% by weight.
In any embodiment of the process of the invention, the resulting silyl (meth)acrylate copolymer (A-2) preferably has a weight-average molecular weight (Mw) of 3,000 to 100,000.
The antifouling paint composition according to the invention comprises the first silyl (meth)acrylate copolymer (A-1) or the second silyl (meth)acrylate copolymer (A-2), and/or further comprises various additives.
More specifically, in the antifouling paint composition (P) of the invention, the first silyl (meth)acrylate copolymer (A-1) is contained as a film-forming component.
In the antifouling paint composition (Q) of the invention, at least the first silyl (meth)acrylate copolymer (A-1), an antifouling agent (B) whose representatives are copper and/or a copper compound, and a vinyl ether (co)polymer (E) and/or an elution accelerating component (F) are contained.
In the antifouling paint composition (R) of the invention, the second silyl (meth)acrylate copolymer (A-2) is contained as a film-forming component and an elution controlling component.
That is, the antifouling paint composition (P) of the invention comprises the silyl (meth)acrylate copolymer (A-1).
The antifouling paint composition (P) of the invention preferably comprises the silyl (meth)acrylate copolymer (A-1) and an antifouling agent (B).
The antifouling paint composition (P) of the invention preferably comprises the silyl (meth)acrylate copolymer (A-1), an antifouling agent (B) and zinc oxide (C).
The antifouling paint composition (P) of the invention preferably comprises the silyl (meth)acrylate copolymer (A-1), an antifouling agent (B) and an inorganic dehydrating agent (D).
The antifouling paint composition (P) of the invention preferably comprises the silyl (meth)acrylate copolymer (A-1), an antifouling agent (B), zinc oxide (C) and an inorganic dehydrating agent (D).
In any embodiment of the antifouling paint composition (P) of the invention, the antifouling agent is preferably copper and/or a copper compound (B-1).
In any embodiment of the antifouling paint composition (P) of the invention, the antifouling agent is preferably a pyrithione compound (B-2).
In any embodiment of the antifouling paint composition (P) of the invention, the antifouling agent preferably comprises copper and/or a copper compound (B-1) and a pyrithione compound (B-2).
In any embodiment of the antifouling paint composition (P) of the invention, the unsaturated monomer constituent units (c) are preferably those derived from at least one compound selected from (meth)acrylic esters, styrene and vinyl esters.
The second antifouling composition (Q) of the invention comprises the silyl (meth)acrylate copolymer (A-1), an antifouling agent (B), and a vinyl ether (co)polymer (E) containing constituent units derived from a vinyl ether represented by the formula (V) H2Cxe2x95x90CHOxe2x80x94R (wherein R is a hydrocarbon group) and/or an elution accelerating component (F).
More specifically, the antifouling paint composition (Q) of the invention preferably comprises the silyl (meth)acrylate copolymer (A-1), an antifouling agent (B) and the vinyl ether (co)polymer (E).
The antifouling paint composition (Q) of the invention preferably comprises the silyl (meth)acrylate copolymer (A-1), an antifouling agent (B) and an elution accelerating component (F).
The antifouling paint composition (Q) of the invention preferably comprises the silyl (meth)acrylate copolymer (A-1), an antifouling agent (B), the vinyl ether (co)polymer (E) and an elution accelerating component (F).
In the antifouling paint composition (Q) of the invention, the antifouling agent (B) is preferably copper and/or a copper compound.
In the antifouling paint composition (Q) of the invention, the elution accelerating component (F) is preferably at least one substance selected from rosin, rosin derivatives, naphthenic acid and metallic salts thereof.
In any embodiment of the antifouling paint composition (Q) of the invention, the unsaturated monomer constituent units (c) are preferably those derived from at least one compound selected from (meth)acrylic esters, styrene and vinyl esters.
The third antifouling paint composition (R) of the invention comprises the silyl (meth)acrylate copolymer (A-2).
The antifouling paint composition (R) of the invention preferably comprises the silyl (meth)acrylate copolymer (A-2) and an antifouling agent (B).
The antifouling paint composition (R) of the invention preferably comprises the silyl (meth)acrylate copolymer (A-2), an antifouling agent (B) and zinc oxide (C).
The antifouling paint composition (R) of the invention preferably comprises the silyl (meth)acrylate copolymer (A-2), an antifouling agent (B) and an inorganic dehydrating agent (D).
The antifouling paint composition (R) of the invention preferably comprises the silyl (meth)acrylate copolymer (A-2), an antifouling agent (B), zinc oxide (C) and an inorganic dehydrating agent (D).
The antifouling paint composition (R) of the invention preferably further comprises an elution accelerating component (F).
The antifouling paint composition (R) of the invention preferably further comprises a vinyl ether (co)polymer (E) containing constituent units derived from a vinyl ether represented by the formula (V) H2Cxe2x95x90CHOxe2x80x94R (wherein R is a hydrocarbon group).
In the antifouling paint composition (R) of the invention, either copper and/or a copper compound (particularly copper and/or an inorganic copper compound (B-3)) or an organic antifouling agent (B-4), or both of them are preferably used as the antifouling agent (B).
In the antifouling paint composition (R) of the invention, the organic antifouling agent (B-4) is preferably at least one organic antifouling agent selected from the group consisting of metal pyrithiones, pyridine-triphenylborane, amine-triphenylborane, N,N-dimethyldichlorophenylurea, 2,4,6-trichlorophenylmaleimide, 2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine, 4,5-dichloro-2-n-octyl-4-isothiazoline-3-one and 2,4,5,6-tetrachloroisophthalonitrile.
In the antifouling paint composition (R) of the invention, the organic antifouling agent (B-4) is preferably 4,5-dichloro-2-n-octyl-4-isothiazoline-3-one.
In the antifouling paint composition (R) of the invention, the organic antifouling agent (B-4) is preferably a combination of metal pyrithione and at least one organic antifouling agent selected from the group consisting of N,N-dimethyldichlorophenylurea, 2,4,6-trichlorophenylmaleimide, 2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine, 4,5-dichloro-2-n-octyl-4-isothiazoline-3-one and 2,4,5,6-tetrachloroisophthalonitrile.
In the antifouling paint composition (R) of the invention, the organic antifouling agent (B-4) is preferably a combination of copper pyrithione and/or zinc pyrithione and 4,5-dichloro-2-n-octyl-4-isothiazoline-3-one.
In the antifouling paint composition (R) of the invention, the elution accelerating component (F) is preferably at least one substance selected from rosin, rosin derivatives, naphthenic acid and metallic salts thereof.
In the antifouling paint composition (R) of the invention, the unsaturated monomer constituent units (f) are preferably those derived from at least one compound selected from (meth)acrylic esters, styrene and vinyl esters of organic carboxylic acids.
The antifouling coating film according to the invention is formed from the antifouling paint composition described above.
The method of antifouling a hull or an underwater structure according to the invention employs the antifouling paint composition described above.
The hull or the underwater structure according to the invention is a hull or an underwater structure whose surface is coated with a coating film formed from the antifouling paint composition described above.
According to the present invention, there is provided a silyl (meth)acrylate copolymer which can produce an antifouling paint capable of forming an antifouling coating film which hardly suffers from occurrence of cracks, has excellent adhesive strength and thereby hardly suffers from peeling, can be favorably controlled in the hydrolysis rate, is excellent in antifouling performance (antifouling activities), antifouling properties, particularly antifouling properties in a highly fouling environment, and long-term antifouling properties, and is well-balanced among these properties. A process for preparing the silyl (meth)acrylate copolymer is also provided. Further, an antifouling paint composition capable of forming such an antifouling coating film as mentioned above is provided.